JPH10195432A - Fluorescent substance for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluorescent substance for a plasma display panel capable of remarkably raising the luminous intensity and color purity and improving the emission efficiency in a red region by providing the fluorescent substance with a specific chemical composition. SOLUTION: This fluorescent substance for a plasma display panel is preferably represented by the formula [0<(a)<=0.90; 0.01<=(b)<=0.20], e.g. (Y0.53 Gd0.40 Eu0.07 )2 O3 . The value of (a) is preferably within the range of 0.4<=(a)<=0.6. The fluorescent substance is obtained by weighing prescribed amounts of a compound capable of readily producing Y2 O3 by heat treatment such as yttrium oxide (Y2 O3 ) or an oxide, a carbonate or a nitrate of Y and a compound capable of similarly and easily producing Gd2 O3 by heat treatment, dissolving the compounds in an acid such as hydrochloric or nitric acid, adding oxalic acid thereto, precipitating the compounds as oxalates and then decomposing the coprecipitated oxalates at 1,000 deg.C for several hours.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor for a plasma display panel, and more particularly, to a phosphor for a plasma display panel which has improved color purity and can greatly increase luminous efficiency when used as a light emitting layer of the plasma display panel. The present invention relates to a phosphor and a plasma display panel using the phosphor.

[0002]

2. Description of the Related Art In recent years, a plasma display panel (PDP) has been widely used as a television receiver instead of a conventional large and heavy cathode ray tube (CRT), which has suppressed the stage of commercialization. PDPs are easier to be thinner and lighter than conventional cathode-ray tube type CRTs due to their structural features. Therefore, PDPs have large screens and are required to realize wall-mounted TVs that require further thinning. It is in the spotlight as an opportunity.

FIG. 2 is a sectional view schematically showing the structure of a plasma display panel. That is, the plasma display panel 1 has a structure in which a front-side substrate 2 and a back-side substrate 3 such as glass, which are translucent, are arranged to face each other so as to have a predetermined discharge space 10. A light-emitting layer 5 containing phosphor 4 particles is formed on the inner surface of the substrate, while a large number of striped positive and negative electrodes 6 and 7 are arranged on the inner surface of the rear substrate 3. Each of the electrode groups 6 and 7 is covered with a dielectric layer 8, and the surface of the dielectric layer 8 is further covered with a protective layer 9. The height of the discharge space 10 is set to about 0.1 mm, and a helium (He) gas or a neon (Ne) gas is provided in the discharge space 10 in order to generate ultraviolet rays that excite the phosphor 4 when discharged. A mixed gas 11 composed of several vol.% Xenon (Xe) gas is sealed.

[0004] The plasma display panel 1 having the above configuration.
In the above, the phosphor 4 is excited by vacuum ultraviolet (VUV) light having a wavelength of 147 nm emitted in resonance with the xenon of the mixed gas 11 in the discharge spaces 10 of the electrodes 6 and 7, so that visible light is emitted and a predetermined image is obtained. Is displayed.

The above plasma display panel (PD)
Regarding P), improvement of image quality has been the biggest issue in the past, and vigorous improvement was aimed at achieving both the brightness representing the screen brightness and the contrast ratio, which is the ratio of black and white brightness. Is being promoted. However, at this time, the image quality equivalent to that of a CRT such as a cathode ray tube has not yet been reached.
There is plenty of room for further improvement.

At present, a plasma display panel (PD)
As a light-emitting material for P), a phosphor for general fluorescent lamps and an improved product thereof are used. However, while the fluorescent substance for a fluorescent lamp converts ultraviolet light having a wavelength of 254 nm into visible light, the basic principle of a PDP is to convert ultraviolet light having a wavelength of 147 nm into visible light. Due to such a difference in the excitation source, a fluorescent material for a fluorescent lamp does not always have excellent characteristics as a fluorescent material for a PDP. However, since there is no use of a phosphor for converting ultraviolet light of a wavelength of 147 nm into visible light other than PDP,
At present, the development of new phosphors for PDPs having excellent characteristics has been delayed.

Conventionally, a plasma display panel (PD)
Examples of the red light-emitting phosphor P) include the general formula Y ₂ O ₃ : Eu.
As shown by the above, a phosphor activated with trivalent europium is widely used. This phosphor is a rare earth oxide phosphor having an emission peak wavelength at 611 nm.

[0008]

However, when the red-light-emitting phosphor represented by the above general formula Y ₂ O ₃ : Eu is excited by ultraviolet light having a wavelength of 147 nm, the emission intensity in the red region is low, and the display intensity is low. However, there has been a problem that the color purity required for the above is insufficient. Therefore, when a PDP is formed by including this phosphor in a fluorescent film, it is extremely difficult to improve the luminous efficiency and color purity of the PDP, and the PDP has a high luminous intensity in the red region. On the other hand, developing a phosphor with high color purity has been a technical issue.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in particular, a phosphor capable of improving color purity and improving luminous efficiency of a plasma display panel, and a plasma display using the phosphor. It aims to provide a panel (PDP).

[0010]

In order to achieve the above object, the present inventors have prepared various kinds of phosphors by adding various elemental components to a Y ₂ O ₃ : Eu-based phosphor, A phosphor layer having a light-emitting layer formed by using these phosphor compositions
DP was prepared, and the effects of the types and amounts of the added elements on the luminous efficiency and color purity of each phosphor and PDP were comparatively investigated by experiments.

As a result, when gadolinium (Gd) is solid-dissolved in the Y ₂ O ₃ : Eu-based phosphor, a phosphor having a high emission rate and a good color purity can be obtained under the excitation of ultraviolet light having a wavelength of 147 nm. It has been found that when this phosphor is contained in a light emitting layer of a PDP, a PDP excellent in luminous efficiency and color purity can be obtained for the first time. The present invention has been completed based on the above findings.

Namely, the phosphor of the present invention have the general formula _{(Y 1-ab Gd a Eu} b) 2 O 3 ( where, 0 <a ≦ 0.
90, 0.01 ≦ b ≦ 0.20). More preferably, the value of a is in the range of 0.4 ≦ a ≦ 0.6.

Furthermore plasma display panel according to the present invention, the general formula _{(Y 1-ab Gd a Eu} b) 2 O 3 ( where, 0 <a ≦ 0.90,0.01 ≦ b ≦ 0.20) It is characterized by comprising a light emitting layer containing the phosphor represented.

Here, the reason for limiting the range of the values of a and b in the general formula will be described below.

Gd (gadolinium) constituting the oxide is
The solid solution in the phosphor has an effect of increasing the emission energy in the red region. In the present invention, the oxide (Gd ₂ O ₃ ) is contained so that the weight ratio a of the oxide (Gd ₂ O ₃ ) becomes 0.90 or less. . This is because when the content exceeds 0.90, the emission intensity becomes insufficient. A preferable range of the weight ratio a is a range of 0.05 or more and less than 0.90. Furthermore, the range of 0.4 or more and 0.6 or less is more preferable.

On the other hand, Eu (Europium) acts as an activator for increasing the luminous efficiency of the phosphor, and is added at a weight ratio b to Y of 0.01 to 0.20. If the proportion by weight b is less than 0.01, the luminous efficiency is insufficient. If it exceeds 0.20, the luminous efficiency is rather lowered due to the quenching of the concentration of Eu.

The production method (synthesis method) of the phosphor according to the present invention is not particularly limited, and the phosphor is produced by blending the following various phosphor materials so as to have a predetermined component composition. That is, yttrium oxide (Y ₂ O ₃ ) or a compound such as an oxide, carbonate or nitrate of Y, which easily generates Y ₂ O ₃ by heat treatment, and gadolinium oxide (Gd ₂ O ₃ ) or Gd Oxides, carbonates,
Gd ₂ can be easily formed by heat treatment such as nitrate.
A compound generating O ₃ and europium oxide (Eu ₂ O
₃ ) A predetermined amount of a compound which easily generates Eu ₂ O ₃ by heat treatment such as Eu oxide, carbonate, nitrate or the like is weighed and dissolved in an acid such as hydrochloric acid, nitric acid, etc. To precipitate as oxalate. The coprecipitated oxalate is decomposed at 1000 ° C. for several hours to obtain an oxide.
Further, an appropriate amount of flux is added, and the mixture is fired at 1300-1500 ° C. for 4-5 hours. Next, the obtained fired product is pulverized, and further washed and dried to obtain a phosphor according to the present invention.

According to the phosphor having the above structure, Y
_Since Gd is dissolved in the ₂ O ₃ : Eu-based phosphor, the emission intensity and color purity in the red emission region can be greatly increased. Is formed, the luminous efficiency and color purity of the plasma display panel can be greatly improved.

[0019]

Next, an embodiment of the present invention will be described.
This will be described more specifically with reference to the following examples.

Example 1 As a phosphor material, 53 wt% of Y ₂ O ₃ powder and Gd ₂
O ₃ powder 40 wt%, the Eu ₂ O ₃ powder were weighed 7 wt%, and a solution was dissolved in an appropriate amount of nitric acid 70 ° C.. A predetermined amount of oxalic acid (H ₂ C ₂ O ₄ .2H ₂ O) was added thereto to precipitate oxalic acid. The obtained coprecipitated oxalate was thermally decomposed at 1000 ° C. for 3 hours to obtain an oxide. This oxide was fired at 1400 ° C. for 4 hours. Further, the obtained fired product is pulverized by a ball mill and further subjected to a washing treatment to obtain a composition formula (Y _0.53 Gd _0.40 Eu _0.07 ) ₂ O.
A phosphor represented by ₃ was obtained.

COMPARATIVE EXAMPLE The procedure of Example 1 was repeated except that Gd ₂ O ₃ was not added at all.
A phosphor of Comparative Example represented by _0.93 Eu _0.07 ) ₂ O ₃ was obtained.

FIG. 1 is a graph showing emission excitation spectrum distributions of the phosphors according to Example 1 and Comparative Example. Gd
The radiant energy of the phosphor of Example 1 containing
It turned out that it increased compared with the fluorescent substance of the comparative example which does not contain d.

In order to evaluate the characteristics of this phosphor, the phosphor was irradiated with ultraviolet light having a wavelength of 147 nm to be excited, and the emission luminance L1 and chromaticity of the obtained emission spectrum were measured. Note that the emission luminance L1 of the phosphor is Gd ₂ O ₃
The emission luminance of a conventional phosphor containing no (comparative example) is relatively shown as a reference value of 100. The emission chromaticity (x, y) of the phosphor was measured at 0 hours and 1000 hours after the emission, and the change value Δx of the emission chromaticity was from the chromaticity x ₀ at the time of the initial emission to 1000 hours after the emission. Chromaticity x
_This is a value obtained by subtracting ₁₀₀₀ . Δy is also obtained for the chromaticity y. Regarding the emission chromaticity, the chromaticity of the conventional phosphor (comparative example) is relatively shown as a reference value (0, 0).

Further, a light emitting layer containing the phosphor according to Example 1 was formed, and a plasma display panel as shown in FIG. 2 was manufactured.
The light emission intensity L3 after lighting for 000 hours was measured, and 1
The ratio (L3 / L2) of the luminescence intensity L3 to the initial value L2 after 000 hours was calculated as a maintenance ratio. Table 1 shows the measurement calculation results.

As shown in Table 1, the emission luminance of the phosphor according to Example 1 was improved to 110% as compared with the conventional phosphor containing no Gd ₂ O ₃ (comparison). Further, the chromaticity was X = + 0.020 and Y = −0.020 with respect to the comparative example, and it was apparent that the luminous efficiency was significantly increased and the color purity was improved.

Further, the emission intensity immediately after the production of the plasma display panel (PDP) using the phosphor according to the example 1 was measured in a comparative example (Y _0.93 Eu) which is a conventional phosphor.
_0.07 ) 11 against the emission intensity of PDP using ₂ O ₃
3%. Further, the chromaticity was X = + 0.
025, Y = −0.025. In addition, the maintenance rate of the light emission intensity after lighting for 1000 hours is also 0.90,
The PDP was improved as compared with 0.85 of the comparative example, and excellent in both luminous efficiency and color purity were obtained.

Example 2 As a phosphor material, 70 wt% of Y ₂ O ₃ powder and Gd ₂
O ₃ powder 20 wt%, the Eu ₂ O ₃ powder were weighed 10 wt%, and the solution was dissolved in an appropriate amount of nitric acid 70 ° C.. A predetermined amount of oxalic acid (H ₂ C ₂ O ₄ .2H ₂ O) was added thereto to precipitate oxalic acid. The obtained coprecipitated oxalate was thermally decomposed at 1000 ° C. for 3 hours to obtain an oxide. This oxide was fired at 1400 ° C. for 4 hours. Further, the obtained fired product is pulverized by a ball mill and further subjected to a washing treatment to obtain a composition formula (Y _0.70 Gd _0.20 Eu _0.10 ) ₂
A phosphor represented by O ₃ was obtained.

In order to evaluate the characteristics of this phosphor, the phosphor was irradiated with ultraviolet rays having a wavelength of 147 nm to be excited, and the emission luminance L1 and chromaticity of the obtained emission spectrum were measured.

Further, a phosphor-containing light emitting layer according to Example 2 was formed, and a plasma display panel as shown in FIG. 2 was manufactured.
The light emission intensity L3 after lighting for 000 hours was measured, and 1
The ratio (L3 / L2) of the luminescence intensity L3 to the initial value L2 after 000 hours was calculated as a maintenance ratio. Table 1 shows the measurement calculation results.

As shown in Table 1, the emission luminance of the phosphor according to Example 2 was improved to 108% as compared with the conventional phosphor containing no Gd ₂ O ₃ (Comparative Example). Further, the chromaticity was X = + 0.015, Y = −0.020 with respect to the comparative example, and the luminous efficiency was obviously significantly increased, and the result that the color purity was improved was obtained.

The emission intensity immediately after the production of the plasma display panel (PDP) using the phosphor according to Example 2 was measured in a comparative example (Y _0.93 Eu) which is a conventional phosphor.
_0.07 ) 11 against the emission intensity of PDP using ₂ O ₃
It was 0%. Further, the chromaticity was X = + 0.
018, Y = -0.023. In addition, the maintenance ratio of the light emission intensity after lighting for 1000 hours is also 0.88,
The PDP was improved as compared with 0.85 of the comparative example, and excellent in both luminous efficiency and color purity were obtained.

Example 3 As a phosphor material, 20 wt% of Y ₂ O ₃ powder and Gd ₂
O ₃ powder 65 wt%, the Eu ₂ O ₃ powder were weighed 15 wt%, and the solution was dissolved in an appropriate amount of nitric acid 70 ° C.. A predetermined amount of oxalic acid (H ₂ C ₂ O ₄ .2H ₂ O) was added thereto to precipitate oxalic acid. The obtained coprecipitated oxalate was thermally decomposed at 1000 ° C. for 3 hours to obtain an oxide. This oxide was fired at 1400 ° C. for 4 hours. Further, the obtained fired product is pulverized by a ball mill and further subjected to a washing treatment to obtain a composition formula (Y _0.20 Gd _0.65 Eu _0.15 ) ₂
A phosphor represented by O ₃ was obtained.

In order to evaluate the characteristics of this phosphor, the phosphor was irradiated with ultraviolet rays having a wavelength of 147 nm to be excited, and the emission luminance L1 and chromaticity of the obtained emission spectrum were measured.

Further, a phosphor-containing light emitting layer according to Example 3 was formed, and a plasma display panel as shown in FIG. 2 was manufactured.
The light emission intensity L3 after lighting for 000 hours was measured, and 1
The ratio (L3 / L2) of the luminescence intensity L3 to the initial value L2 after 000 hours was calculated as a maintenance ratio. Table 1 shows the measurement calculation results.

As shown in Table 1, the emission luminance of the phosphor according to Example 3 was improved to 115% as compared with the conventional phosphor containing no Gd ₂ O ₃ (Comparative Example). Further, the chromaticity was X = + 0.025 and Y = −0.020 with respect to the comparative example, and it was apparent that the luminous efficiency was significantly increased and the color purity was improved.

The emission intensity immediately after the production of the plasma display panel (PDP) using the phosphor according to Example 3 was measured in the comparative example (Y _0.93 Eu) which is a conventional phosphor.
_0.07 ) 11 against the emission intensity of PDP using ₂ O ₃
8%. Further, the chromaticity was X = + 0.
030, Y = -0.025. In addition, the maintenance ratio of the light emission intensity after lighting for 1000 hours is 0.91, and
The PDP was improved as compared with 0.85 of the comparative example, and excellent in both luminous efficiency and color purity were obtained.

Example 4 As a phosphor material, 40 wt% of Y ₂ O ₃ powder and Gd ₂
O ₃ powder 58 wt%, the Eu ₂ O ₃ powder were weighed 2 wt%, and a solution was dissolved in an appropriate amount of nitric acid 70 ° C.. A predetermined amount of oxalic acid (H ₂ C ₂ O ₄ .2H ₂ O) was added thereto to precipitate oxalic acid. The obtained coprecipitated oxalate was thermally decomposed at 1000 ° C. for 3 hours to obtain an oxide. This oxide was fired at 1400 ° C. for 4 hours. Further, the obtained fired product is pulverized by a ball mill and further subjected to a washing treatment to obtain a composition formula (Y _0.40 Gd _0.58 Eu _0.02 ) ₂ O.
A phosphor represented by ₃ was obtained.

In order to evaluate the characteristics of this phosphor, the phosphor was irradiated with ultraviolet light having a wavelength of 147 nm to excite it, and the emission luminance L1 and chromaticity of the obtained emission spectrum were measured.

Further, a light emitting layer containing the phosphor according to Example 4 was formed, and a plasma display panel as shown in FIG. 2 was manufactured.
The light emission intensity L3 after lighting for 000 hours was measured, and 1
The ratio (L3 / L2) of the luminescence intensity L3 to the initial value L2 after 000 hours was calculated as a maintenance ratio. Table 1 shows the measurement calculation results.

As shown in Table 1, the emission luminance of the phosphor according to Example 4 was improved to 107% as compared with the conventional phosphor not containing Gd ₂ O ₃ (Comparative Example). Further, the chromaticity was X = + 0.015, Y = −0.015 with respect to the comparative example, and it was apparent that the luminous efficiency was significantly increased and the color purity was improved.

Further, the emission intensity immediately after the production of the plasma display panel (PDP) using the phosphor according to Example 4 was measured in a comparative example (Y _0.93 Eu) which is a conventional phosphor.
_0.07 ) 11 against the emission intensity of PDP using ₂ O ₃
It was 0%. Further, the chromaticity was X = + 0.
018, Y = −0.020. In addition, the maintenance rate of the light emission intensity after lighting for 1000 hours is also 0.90,
The PDP was improved as compared with 0.85 of the comparative example, and excellent in both luminous efficiency and color purity were obtained.

Examples 5 to 10 The same treatment as in Example 1 except that the amount of Gd ₂ O ₃ used as the phosphor raw material powder was changed and finally adjusted to the composition shown in Table 1. Example 5
10 phosphors were adjusted.

Then, the emission luminance and chromaticity of each phosphor when irradiated with 147 nm ultraviolet rays were measured in the same manner as in Example 1. In addition, PDPs were manufactured using the phosphors according to Examples 5 to 10, and the light emission intensity and chromaticity immediately after the manufacture and the light emission intensity after light emission for 1000 hours were calculated as the maintenance rates. Table 1 below shows the measurement calculation results.

[0044]

[Table 1]

As is apparent from the results shown in Table 1, Y ₂
In the phosphors of the respective examples in which a predetermined amount of Gd is dissolved in the O ₃ : Eu-based phosphor, the emission luminance and the color purity are significantly improved as compared with the phosphors of the comparative examples which do not contain the above elements. That was confirmed. Also, when a PDP was manufactured using the phosphor of each example, the light emission intensity and color purity immediately after the manufacture and after light emission for a predetermined time significantly increased, and the light emission efficiency and color purity were excellent. It was found that a PDP with a small amount was obtained.

[0046]

As described above, according to the phosphor and the plasma display panel (PDP) of the present invention,
Since the gadolinium (Gd) component is dissolved in the Y ₂ O ₃ : Eu-based phosphor, the emission intensity (brightness) and color purity in the red region can be significantly increased under 147 nm ultraviolet excitation. When the phosphor is contained in a phosphor film (light emitting layer) to form a PDP, the luminous efficiency and color purity of the PDP can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a graph showing a light emission excitation spectrum distribution of a phosphor according to Example 1 of the present invention together with a comparative example.

FIG. 2 is a cross-sectional view schematically showing a structure of a plasma display panel (PDP).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma display panel (PDP) 2 Front side substrate (front glass) 3 Back side substrate (back glass) 4 Phosphor 5 Light emitting layer 6 Positive electrode 7 Negative electrode 8 Dielectric layer 9 Protective layer 10 Discharge space

Claims (4)

[Claims] 1. A general formula _{(Y 1-ab Gd a Eu} b) 2 O 3
(However, 0 <a ≦ 0.90, 0.01 ≦ b ≦ 0.20)
A phosphor for a plasma display panel, characterized by being represented by: 2. The phosphor for a plasma display panel according to claim 1, wherein the value of a is in the range of 0.4 ≦ a ≦ 0.6. 3. A general formula _{(Y 1-ab Gd a Eu} b) 2 O 3
(However, 0 <a ≦ 0.90, 0.01 ≦ b ≦ 0.20)
A plasma display panel comprising a light-emitting layer containing a phosphor represented by the formula: 4. The plasma display panel according to claim 3, wherein the value of a is in a range of 0.4 ≦ a ≦ 0.6.